1. Field of the Invention
The invention relates in general to elevator systems, and more specifically to elevator systems having a plurality of elevator cars under group supervisory control by a system processor or dispatching function.
2. Description of the Prior Art
In a typical elevator system having a plurality of elevator cars under group supervisory control, all hall calls are normally treated alike from a priority view point, unless they are from a special pre-defined floor, such as a lobby floor, a convention floor, or the like; or, the call has been registered beyond a predetermined period of time, i.e., a timed-out call. It is sometimes desirable to provide immediate priority service for a hall call by providing a riser of hall call pushbuttons which are independent of the normal hall call pushbuttons. The pushbuttons of the independent riser are placed in an inconspicuous location; thus, the term "inconspicuous riser" or IR. Calls register on the inconspicuous riser are ignored by the dispatcher function unless the IR feature is activated, such as by a switch in the traffic director's station (TDS). When the IR switch is moved to the "activated" position, a predetermined car, or cars, is removed from group control as soon as it serves any car calls it may already have registered. This IR car will then respond only to hall calls placed on the IR riser, for as long as the IR feature is selected, with a separate dispatcher function handling the IR calls. The hall lanterns are not activated by IR cars serving IR calls. Since the addition of a second dispatcher adds substantially to the cost of implementng the IR feature, it would be desirable to be able to handle an IR riser with the same dispatching function that handles the normal hall call riser, if this result can be achieved without degradation of elevator service to hall calls registered on the permanently enabled riser.